Refrigerants are a family of chemical solutions designed to transfer heat energy from one place to another. Depending on the purpose of equipment using refrigerants and how it’s configured, refrigerants can be used to lower temperatures, raise them, or facilitate evaporation. Typically, refrigerants are part of a closed system in which they transition from a liquid state to a gas and back again. We use them most commonly in HVAC systems and refrigerators and freezers.
Most construction and industrial workers will not find themselves dealing with refrigerants on a regular basis. However, it’s possible they may unexpectedly encounter them during a project. For example, during the demolition phase of a building renovation, crews may cut into an unseen line that carries refrigerants from into HVAC units to outdoor compressor units. That’s why it’s good to have a basic understanding of these refrigerants, the potential hazards associated with coming into contact with them, and steps that can be taken to mitigate those hazards.
Types of refrigerants
The most well-known refrigerants for many years were chlorofluorochemicals (CFC), which generally entered production during the 1930s. In 1936, the first hydrochlorofluorocarbon (HCFC) refrigerant, R-22, became available. R-22 is better known as Freon. For several decades, CFCs and HCFCs dominated the refrigerant market. They were considered to be nontoxic and nonflammable. However, research during the 1980s began to reveal that CFCs caused damage to the ozone layer in the Earth’s stratosphere and that HCFCs contributed to global warming.
The industry has shifted to several hydrocarbon and hydrofluoroolefin formulations that are believed to be safer for the environment. Many older appliances and HVAC systems continue to contain Freon-based refrigerants, which remain safe as long as the refrigerant is not exposed to the atmosphere. There are processes for reclaiming Freon, which provides a supply for the remaining systems.
In addition, there is growing use of propane, isobutane, and a combination of the two in refrigeration equipment, particularly home refrigerators. While these gases are flammable, they do not contribute to the depletion of ozone. Anhydrous ammonia was frequently used before CFCs were developed, and there has been some discussion of expanding its use. However, it is toxic and can corrode many materials. Carbon dioxide was also used long ago as a refrigerant and is again being considered. Its nature requires high-pressure equipment.
Health risks and precautions
Overall, fluorocarbon refrigerants have a low toxicity to humans. Intentionally inhaling concentrated refrigerant can be fatal, and exposures to high levels of the refrigerant can lead to drowsiness and a loss of concentration. Moving the victim to fresh air usually helps with the symptoms. Skin contact can cause frostbite, which can be treated by flushing the skin with cool water to slowly warm the skin.
Whenever working around refrigerants or where there is a potential for leakage, it’s important to provide adequate ventilation. That’s especially true when working in confined areas. Refrigerant vapors are heavier than air, so there is a danger of oxygen displacement in confined spaces. If there is a leak, the area should be evacuated until the vapors have dissipated. Because some refrigerants are flammable, it’s important to avoid exposure to open flames and other heat sources. As with any chemicals, workers should review the product label and the Material Safety Data Sheet (MSDS) before handling refrigerants.
Safe handling processes
Training is important for workers who regularly handle refrigerants. Companies that use refrigerants are expected to create a plan for compliance with EPA refrigerant regulations and designate a compliance manager for each facility.
Cylinders for use with returnable refrigerant are required to comply with U.S. Department of Transportation (DOT) regulations. Cylinders should never be filled more than 80 percent, or 60 percent if the cylinder may be in an environment of more than 130 degrees. While cylinders are equipped with a combined liquid/vapor valve for safety, it cannot eliminate all hazards. Tanks may rupture or an unexpected flow may occur through a damaged valve.
Any cylinders that have been rusted, dented, or otherwise damaged should be take out of service. All cylinders should be stored upright in dry locations, with valves at the top. When cylinders must be moved, they should be strapped onto a wheeled device. Cylinders should never be rolled. Before being transported, the cylinders should be properly identified in accordance with DOT regulations. Handling cylinders carelessly can cause damage to the cylinders themselves or the attached valves, which can lead to a release of vapors.
In work settings in which refrigerants and related equipment are in regular use, engineering solutions such as the use of vapor sensors and alarms, as well as increased ventilation, can minimize the hazards associated with a leak.